Generally, image data for displaying an image is processed by the graphics controller of a host apparatus, a personal computer (PC), and the resultant image data is transmitted to a display device. For a CRT, which currently is the main device used as a monitor (panel), UXGA (Ultra Extended Graphics Array) (1600×1200 dots) is the preeminent available image size. With this image size, a conventional graphics controller that outputs raster data can easily display an image, and only one monitor cable is required for the transmission of the image data.
As the development of display devices, such as liquid crystal displays (LCDs), has progressed, however, great differences have appeared in the processing capabilities of host apparatuses and display devices. For example, the display resolutions available with QXGA (Quad Extended Graphics Array) (2048×1536 dots) capable displays have recently been surpassed by those of large, higher-resolution monitors (panels), e.g., the high-resolution (super high resolution) QSXGA (Quad Super Extended Graphics Array) (2560×2048 dots) and QUXGA (Quad Ultra Extended Graphics Array) (3200×2400 dots) monitors, but while these super high resolution monitors are gradually reaching the point where they can be used for practical applications, system power and graphic controller capabilities have not kept pace and can not use the super high resolution monitors to present satisfactory displays. That is, at present, driving one of the above described monitors is difficult for a conventional graphics system comprising a set consisting of a monitor cable and a raster transfer graphics card, which is available and will, undoubtedly, continue to be employed.
With one large high-resolution monitor driving method, multiple sets of graphics cards and cables are prepared, and not only is the monitor changed but also an OS or a driver, so that a single raster input panel is handled as multiple raster input panels. However, according to this method, since the number of graphics cards that can be mounted on a PC is limited physically, it is difficult for drawing engines mounted on the individual graphics cards to be operated synchronously. As a result, not only is it difficult to provide a satisfactory image quality for a full-screen display for a moving picture, but also it is difficult to do this for a limited application, such as DTP (Desk Top Publishing). In addition to the image quality problem, for system configuration large investments will be required of graphics card and monitor makers, and of users.
Another method has been studied whereby a frame memory is mounted on a high-resolution panel or a monitor connection device that is positioned between a high-resolution panel and a host apparatus. When a frame memory is provided for a monitor, a specific drawing command is not processed by the host, and before image data is rendered it is transmitted to the monitor whereby it is translated to perform drawing. Thus, the amount of data to be transmitted can be reduced. One further system has been studied that is connected via a network to a client monitor, for example, such as a PC that includes a central processing unit, a communication device and a drawing device, and that outputs, to the client monitor, the results of an application executed by a server. Since this system can considerably reduce the amount of data that must be transmitted along a communication path constituted by a network, ethernet can be selected for use as a communication path.
As is described above, when frame memories are provided for monitors, displays on high-resolution panels are enabled, even when there are no drastic improvements in the functions provided hosts. However, the current techniques require that monitors function the same as common PCs. Thus, when the level of the functions (the same functions as PCs) required of monitors can be reduced, costs can be reduced considerably. Especially when compatibility with currently employed raster monitors can be obtained and conventional graphics raster transfer systems can be employed, high-resolution panels can be easily driven without additional expensive investments being required, and it can be further expected that large, high-resolution panels will be widely used.
To resolve the above described technical problems, it is one object of the present invention to drive a large, high-resolution monitor (panel) merely by making an extremely small change to a conventional system.
It is another object of the present invention to drive, within a limited transfer band, a large, high-resolution monitor that conventionally can not be supported.